Carburetor



W. STURM CARBURETOR Jan. 5, 1932;

Filed March 29, 1928 w eabuum Patented Jan. 5, 1932 UNITED STATES PATENT OFFICE WIl'JHELM STURM, OF STUTTGABT, GERMANY, ASSIGNOR TO ROBERT mSCE AKTIEN- GESELLSGEAFT, OF STUTTGART, GERMANY CABBURETOR Application filed liarch 29, 1928, Serial No. 265,778, and in Germany March 29, 1927.

The present invention relates to carburetorsand more particularly to that type of carburetor in which the float chamber is connected with the main Venturi tube and the fuel is sucked out of the float chamber through an auxiliary Venturi tube arranged in the main Venturi tube.

tomatic suction of the fuel from the tank into the float chamber is no longer obtained! 7 In the carburetor according to the present invention the vacuum in the Venturi tube ismaintained at both low and high speeds so that improvement in the atomization is effected and at the same time the vacuum in the float chamber is maintained so high as to provide sufficient feed of the fuel into the carburetor even under unfavorable conditions for example in cases where the auto-' matic vacuum tank lies at a substantial height above the main fuel tank. This result is accomplished by the provision of an element which regulates the cross section of the air entrance orifice to the carburetor and is actuated either automatically by the air suction, or" positively in combination with the throttle control. I

Figure 1 shows diagrammatically one form of construction 'in vertical section.

Figure 2 is a similar view showing a modified form of construction. The. Venturi tube 0 is arranged at the side of the mixing pipe (1 and is of very narrow cross section. The free space 1 laterally of the Venturi tube 0 is closed by a butterfly valve 2 consisting of two vanes, the longer one of which keeps the valve closed under its own weight whilst the shorter acts as a damping surface to compensate for oscillations. 2 by the air suction is effected by the lifting of the long vane to a greater or lesser extent.

The automatic actuation of the valve At low engine speeds, the valve 2 remains closed and the whole of the air suction flows through the narrow Venturi tube 0, causing an increase in the atomization of the fuel and an increase in the degree of vacuum in the float chamber. With increasing engine speeds, the valve 2 begins to open until it is completely open for maximum engine power.

The quantlty of ejected fuel must however be intimately balanced according .to variation of cross section of the air orifice, as when the valve 2 is closed the submerged jet 5 would supply too much fuel. For this purpose the mouth 1 of the duct m is situated near the valve 2 in the chamber 1. When the valve 2 is closed, no flow of air takes place in the chamber 1, and consequently there is a much smaller vacuum at the mouth n than in the atomizing nozzle is, so that a large quantity of air enters the nozzle and thereby reduces the delivery of fuel by the jet The amount of air entering is determined by the jet t as soon as the valve 2 opens.

air current is set up also in the chamber 1 and the mouth n, which increases the vacuum at the mouth n and baflies the air entering the nozzle is through the jet t and thereby causes increase in the fuel delivered by the jet 2'.

Exact adjustment of the delivery of fuel by the jet 2' to the position of the valve 2 at I any instant is thus obtained.

The valve 2 may however also be positively actuated in conjunction with the throttle adjustment as shown in Figure 2. The p1voted lever 3 connected with the valve 6 by a link 4 presses on the arm 5 of the valve 2 when the valve 6 is opened to a predetermined extent, for example half open, so that until this predetermined position of the valve 6 is reached the Whole of the suction air flows through the narrow air jet 0.

In this case the vanes of the valve 2 may be equal in size.

What I claim is: 1. A carburetor comprising in combination an air valve, a float chamber, a mixing tube, a main venturi connected with the air space However, with increasing engine speed an of said float chamber and an auxiliary venturi within the mam venturi, having connection with the fuel space of said float chamber,

both venturis being located to one side of the mixing tube so as to provide a lateral passage tion a main air valve, a float chamber, a mixing tube enclosing a main venturi connected with the air space of said float chamber and an auxiliary venturi within the main venturi having connection with the fuel space of said float chamber, means to control the cross section for the air-flow in a passage located externally to said venturis and connecting the air-space of the mixing tube before the main venturi with the mixture space of said tube behind the main venturi and means for automatically coupling said secondary air passage controlling. means with the main air valve after the main valve has opened to a certain degree. I

3. A carburetor comprising in combination an air valve, a float chamber, a mixing tube, a main venturi connected with the air space of said float chamber and an auxiliary venturi within the main venturi, a fuel duct leadingfrom the fuel space of said float chamber to the throat of the auxiliary venturi, means to control the cross-section for the air-flow in a passage located externally to said venturis and connecting the air space of the mixing tube before the main venturi with the mixture space of said tube behind the main venturi, and an air tube leading to the fuel duct from the float chamber and having its orifice in said passage.

4. A carburetor comprising in combination a main air valve, a float chamber, a mixing tube enclosing a main venturi connected with the air space of said float chamber and an auxiliary venturi within the main venturi, a fuel duct leading from the fuel space of said float chamber to the throat of the auxiliary venturi, means to control the cross-section for the air flow in a passage located externally to said venturis and connecting the air space of the mixing tube before the main venturi with the mixture space of said tube behind the main venturi, an air tube leading to the fuel duct from the float chamber and having its orifice in said connecting passage, and means for automatically coupling said secondary air passage controllingmeans with the main air valve after this valve has opened to a certain degree.

5. A carburetor comprising in combination an air valve, a float chamber, a mixing tube enclosing a main venturi connected to the air space of said float chamber and an auxiliary venturi within the main venturi, a fuel duct leading from the fuel space of said float chamber to the throat of the auxiliary ventun, means to control the cross section for air flow in a passage of the mixing tube located around the main venturi, an air tube leading to the fuel duct from the float chamber'and having its orifice in said connecting passage in front of said control means.

6. A carburetor comprising in'combination a main valve, a float chamber, a mixing tube enclosing a main venturi connected to the air space of said float chamber and an auxiliary venturi within saidmain venturi, a fuel duct leading from the fuel space of said float chamber to the throat of the auxiliary venturi, means to control the cross-section for air flow in a'passage of the mixing tube located around the main venturi, an air tube leading to the fuel duct from the float chamber and having its orifice in said connecting passage in front of said control means and means for automatically coupling said secondary air passage controlling devices with the main air valve after this valve has opened to a certain degree.

7. A carburetor comprising in combination an air valve, a float chamber, a mixing chamber enclosing a main venturi connected to the air space of said float chamber and an auxiliaryventuri within said main venturi, a fuel duct leading from the fuel space of said float chamber to the throat of the auxiliary venturi, both venturis being located to one side of the mixing tube so as to provide a lateral passage of air, a butterfly valve controlling said passage of air, an air tube leading to the fuelduct and having its orifice in said lateral passage before the butterfly valve.

'8. A carburetor comprising in combination a main air valve, a float chamber enclosin a main venturi connected to the air space 0 said float chamber and an auxiliary venturi within said main venturi, a fuel duct leading from the fuel space of said float chamber to the throat of the auxiliary venturi, both ven-- turis being located to one side of the mixing tube so as to provide a lateral passage of air, a butterfly valve controlling said passage of air, an air tube leading to the fuel duct and having its orifices in said lateral passage before the butterfly valve, and means for automatically coupling said secondary air passage controlling means with the main air valve after this valve has opened to a certain de gree.

9. A carburetor comprising in combination a mixing tube, afloat chamber, a main venturi enclosed in said tube and having a connection from its suction zone to the air space of said float chamber, an auxiliary venturi within said main venturi and connected with the fuel space of said float chamber, means providing a passage for the substantialflow of air around said main venturi from the air space before the main venturi fio the mix= ture space of said mixing tube behind the main venturi, and means located in said assage to control the cross-section for air ow therein in accordance with the suction developed in said passage.

In testimony whereof I have hereunto, afiixed my signature.

WILHELM STURM. 

